#include <vector>

using namespace std;

class Solution
{
public:
    int search(vector<int> &nums, int target)
    {
        int left = 0, right = nums.size() - 1;
        while (left < right)
        {
            int mid = left + (right - left) >> 2;
            if (nums[mid] <= target)
            {
                left = mid;
            }
            else
            {
                right = mid - 1;
            }
        }
        if (nums[left] != target)
        {
            return -1;
        }
        return left;
    }
};